Turf mowers are well known machines used for cutting grass and other vegetation. Such a machine may include a tractor vehicle and a tractor-mounted cutting unit which can driven by the engine of the tractor through a drive train. The drive wheels of the tractor are driven by the tractor engine by way of a transmission which includes a manually operated control.
While various interlock mechanisms and control systems for turf mowers are known, the combined features of and benefits derived from the present invention are not illustrated or taught by those prior inventions. For example, interlock mechanisms are known which prevent operation of the cutting unit during reverse travel of the tractor. Interlock approaches may include mechanical systems, such as disclosed in U.S. Pat. No. 3,984,967, or electro-mechanical systems, such as disclosed in U.S. Pat. Nos. 5,601,512 and 5,314,038. Similarly, other inventions disclose override control systems which allow selective operation of mowing machines under certain circumstances. Such override control systems include "supervisor-switched" systems which may include a switch with a removable key to limit the override decision-making to one or more individual, who may not be the machine operator. A supervisor-switched control system for turf mowers is disclosed in U.S. Pat. No. 5,497,604 to Lonn, and assigned to The Toro Company, assignee herein.